The invention relates to a method of electrochemically machining a workpiece by means of an electrode, comprising the steps of
bringing the workpiece and the electrode into contact with one another, PA1 setting a working distance between the electrode and the workpiece while keeping the gap between the workpiece and the electrode filled with an electrolyte, and PA1 passing an operating current through the electrolyte in the gap via the electrode and the workpiece in order to machine the workpiece. PA1 a base for positioning a workpiece, PA1 a holder for positioning an electrode, PA1 an actuator for moving the holder and the base with respect to one another, PA1 a detection device for detecting contact between the electrode and the workpiece, and PA1 a control unit for controlling the actuator. PA1 increasing the distance between the electrode and the workpiece by a first distance starting from a situation of contact between the electrode and the workpiece, followed by PA1 detecting whether the contact between the electrode and the workpiece is broken, and PA1 increasing the distance between the workpiece and the electrode by a second distance if the detection shows that the contact between the electrode and the workpiece has been broken. PA1 to set a first distance between the electrode and the workpiece, PA1 to detect whether the contact between the electrode and the workpiece is broken, and PA1 to increase the distance between the workpiece and the electrode by a second distance.
The invention further relates to an arrangement for electrochemically machining a workpiece by means of an electrode, in which a working distance is set between the electrode and the workpiece while the gap between the workpiece and the electrode is filled with an electrolyte, and in which the workpiece is machined by passing an operating current through the electrolyte in the gap via the electrode and the workpiece, which arrangement includes
Moreover, the invention relates to a control unit for controlling an actuator in an arrangement for electrochemically machining a workpiece by means of an electrode.
Such a method is known from the publication "Modelling and Monitoring Interelectrode Gap In Pulse Electrochemical Machining" in Annals of the CIRP Vol. 44/1/1995. In the known method a workpiece is machined by means of an electrode in an electrolyte consisting of a 15% solution of NaCl in water. Said publication states that the machining accuracy is higher when a small working distance is provided between the electrode and the workpiece. In a test mode a working distance of at least 0.1 mm is set, after which an operating current is passed through the electrolyte in the gap between the workpiece and the electrode. According to the publication this working distance is usually set by bringing the electrode and the workpiece into contact with one another and subsequently positioning the electrode at a desired distance from the workpiece. A disadvantage of this method is that in the case of a small working distance being set it is not unlikely that a flash-over or a short-circuit occurs between the electrode and the workpiece when the operating current is applied, as a result of which the electrode and/or the workpiece are damaged by the heat produced by the operating current at the location of the flash-over or the short-circuit.